The investigator will develop expertise in visual psychophysics and create a program for exploring processes underlying visual motion perception and pursuit eye movements in human cerebral cortex. The investigator is experienced in eye movement studies and will work with a mentor who is expert in visual perception. While work is monkeys has delineated numerous cerebral areas participating in motion perception and pursuit, less is known about the regions involved in these processes in humans. However, recent developments in function and structural imaging in humans have the potential to advance our knowledge of human cerebral function. The investigator proposes a novel dual approach to localization. Motion perception and pursuit will be studied in patients with lesions mapped by detailed magnetic resonance images (MRI). Concurrently, similar motion perception and pursuit tasks will be given to normal subjects undergoing functional MRI. Lesion and functional imaging will provide complimentary information, and guide each other's progress. Based on hypothesis generated from current knowledge, we will (1) explore potential differences between the use of visual motion in defining the form of objects versus detecting self-motion, (2) study visual motion, feedback, and prediction in pursuit, and (3) follow patients to learn how complex, visual dysfunction recovers after natural human lesions. We will also (4) investigate the intriguing location of the underlying lesion. In sum, the investigator will join sophisticated visual and ocular motor measure to modern neuro-imaging of structure and function. It is anticipated that these studies will advances our knowledge of the human anatomy of motion processing as a system and also develop new approaches to emerging methodology in brain localization.